Apparatus for preheating the air supply for a furnace



Filed June 3, `1940 QosMALLEY ET AL AFPARATUS FOR PREHEAT'ING'HE AIR SUPPLY FOR A FURNACE Feb. 24, 1942,`

- INVENTORS vBY Herma/' 'R M PSEYS i Ufa@ Patented Feb. 2 4, ,.1942

APPARATUsroR PREHEATING 'rim Am "j SUPPLY FORAFURNACE i Oliver Smalley, Pittsburgh, Pa., andrllerbert A. Reece, Cleveland Heights, Ohio, as'signors to Meehanite Metal Corporation, a corporation of Tennessee Application-June 3, 194o,ser ia1 No; 333,468 f7 claims..letzte- 14) v `Ourfinvention relates to -furnaces and'more particularlyto metallurgical furnaces such as cupolas and thelike, and to the 'operation' of the sarne. v Y L The inventiondisclosed herein is directed to the pre-heating of air suppliedy to a metallurgical furnace for the promotion of combustion therein.

11n the following discussion anddescription the operationland structureofacupola for the remelting of metal willbe referred to but it is to be understood that our invention includes the structure and operationof other furnaces and similar deviceswherein a blast of airor other gases is suppliedthrough a plurality of tuyres A orlike openings device;

Th'epresent invention utilizes the heat generated within the cupola for pre-heating the air delivered through "the cupola tuyres to the in` teriorof the cupola. During operation of the cupola'the 'coke or other similar fuel charged into the cupola burns'an'd generates alarge 'amount of -heat within the shaft of the cupola. The hot gasesresulting from thejcombustion of .the c oke penetrate the'charge of coke and metal Within the cupola and arise upY and out throughthe top -to the interior of the furnace orsimilar of thejcupola. "I he heat energy borne by lthese hott gases "is ordinarily lost to atmosphere at the f topof the cupolaexcept'forthesmall'amountof heatradiated through the body of thef cupola along the circumferentialjsides thereof'.

ln pre-heating systems prior to the present vention there has been an attempt to'utilize some ofrthe'heat generatedwithin the cupola by providing wall sections, in lthe sides of the cupola, of

al heat conductingmaterial vsuch'as iron rather` than having them heat insulated completely by the fire brick lining of the. cupola. InA such pre- -vious systems the airto be supplied to the tuyres waspassedalongadjacent, to, and outside of, the wall sectionshavin'g the high d egreevof heat conductivity; "'Insome of 'these systemsof this class@ the vheat conducting wall sections were made `lack of uniformity in the heating'of the total air blast delivered through the system andthere was no assurance ofv a delivery of uniformly heated air to the plurality of tuyres. Moreover, the maximum amount of heat exchange between the hot gases and the'airwas greatly limited by the arrangement of the parts and the `inherent disability of the structure. Other limitations preventing the productionof the desired results in pre-heating air are apparent upon inspection of `the `structure of the previous systems and particularlyin the light of the disclosure of the results obtained from the present invention.

It is an object ofthe present invention to obvia'te the limitations, defects and disadvantages ofthe prior systems.`

Another object of the invention is the provision of animproved system of pre-heating the air supplied to a-"cupola affording results and preadvantages not heretofore known or obsenting tainable.

Another yobject is the provision for the obtaining of themaximum amount of heat from the hot gases of the cupola in pre-heating the air supplied to the. cupola. i Another object is the provision for obtaining a more uniform heating lof the air supplied to a cupola.

Another object is the provision for a distribution of air flow in afsystem to obtain auniform heating of the air supplied to a plurality of cupola tuyres.

hollow to permit the hot gases/to fiowthrough the hollowwall and to thus passthe heat through afrelatively thin shell of "the wall to the air flowing through the air supply 'system on. the `c iutside .-v

ofthe cupola.

The prior systems, however, were subjected to limitations, defects and disadvantages whichjdid not provide for an Aeilicient,and proper pre-heating ofthe air supply. The air passing through' the conduits or wind box of the system was heated a only upon one side, thatis", l'only through the wall nextadjacent to the cupola body. There was a 55 Another object is the provision o f improved apparatus for the utilization of heat generated by a cupola for the efhcient pre-heating of the air suppliedl to the tuyres of the cupola.

Another object is the provision for establishing a more eflicient heat exchange relationship between the hot gases of the cupola and the air beingsupplied 'to the cupola.

` A still further object is the provision of an air pre-heating 'system aior'dingresults not here-'- tofore obtainable.

Other objects and'a fuller understanding ofour invention maybe had by referring to the following description and claims, taken in conjunction with' the accompanying drawing, in,

which: Figure 1 is aV cross-sectional view taken lengthwise ora. cupola and wind boxvembodying our kinventionandfis a -view looking in the direction ofthe arrows I-I of Figure 2;

Figure 2 vis a transverse cross-sectional view taken through the line 2-2 of Figure 1 Figure 3 is a crosssectional view takenlengthwise of a cupola and wind box embodying a modifled form of our invention and is a view looking in the direction of the arrows 3 3 of Figure 4; and

Figure 4 is a transverse cross-sectional .view taken through the line 4-4 of Figure 3.

Inasmuch as the invention disclosed herein is directed particularly to the wind box, the portion of the cupola adjacent thereto and the heating arrangement associated therewith, it has not been considered necessary to show all parts of the cupola nor all views thereof in the'several figures. The portions of the cupola and wind box not shown, however, may be considered as having the usual and well known form. Also, for purposes of simplicity in illustration, the usual tap hole and slag hole are not. shown. It has also been considered unnecessary to illustrate such other openingsas a clean-out door, breast arch or drop-bottom door. lIfhe cupola to which the invention is associated and which is described herein maybe considered, however, as having all of the parts necessary for the usual operation of the same. y

As shown in the several views of the drawing, the cupola body or shell 2| is in the form of a cylindrical shaft, the inner walls of the cupola body 2| being lined by the re brick lining 24. The body 2| and the lining 24 are mounted upon the usual bottom plate 21 and thereby forms the enclosed shaft or stack of the cupola. Suitable supports 26 form a base for the support of the cupola.

A wind box 22 of cylindrical shaft is mounted upon the cupola `body 2| by welding or other suitable means and in the embodiment shown, the outer wall of the cupola body ,forms one of the enclosing walls of the wind box 22. It is therefore seen -from the view of the drawing that the wind box 22 forms an enclosed jacket surrounding the cupola body 2| in such a way that air introduced into the wind box may circulate entirely around the cupola body.

An inlet conduit 23 is in communication with an air blower or other source of an air blast `(not shown) and the inlet conduit 23 is connected to the upper portion of the Wind box 22 so as to afford communication between the air blower and the inlet opening 25 of the wind box 22.

In the cupola illustrated there are six tuyres extending through thewall and lining of the cupola body 2| to establish communication be'- tween the interior of the shaft of the cupola and the lower portion of the wind box 22. All six tuyres 30, 3|, 32, 33, 34 and 35 are shown in dotted lines inl transverse cross-sectional views of the drawing and three of the tuyres 30, 3| and 32`asuseen from the inside of the shaft of the cupola are illustrated in the cross-sectional views taken lengthwise of the cupola. These six tuyres are of substantially equal size and are uniformly spaced around the periphery of the cupola. 'Ihe tuyres enter the cupola body at a low level in the cupola and communicate with the lower portion of the wind box.

Thefdescription of the rst form of the invention is madein conjunction with the showing of Figures 1 and 2. In conjunction wth said gures there is shown an upper partition 31 and a lower partition 38 spaced apart and dividing the wind box into an upper compartment adjacent the inlet 25, a lower compartment adjacent the six tuyres and an intermediate compartment forming the heating chamber 42. A plurality of tubular conduits 39 extend from the partition 31 to 2,273,901 Y' Y u the partition 38 to provide communicationbetween the upper portion and the lower portion of the wind box, the conduits 39 being adapted to accommodate a flow of air down through the wind box from the inlet 25 to the tuyres. The conduits 39 are arranged in regular intervals around the wind box and are of equal size to substantially equalize the owof air therethrough from the wind box inlet to theV plurality of tuyres. The arrangement of the partitions and conduits is such that air is sealed from the heating chamber 42 but as it flows through the tubes 39 is immediately adjacent to the heating chamber.v

A plurality of lower holes 40 extend through the wall of the cupola and provide communication between the interior of the cupola and the heating chamber 42. A plurality of upper holes 4| also extend through the wall of the cupola to provide communication between the interior of the cupola and the heating chamber 42. Hot

gases bearing heat generated by the combustionl within the cupola may flow outwardly through the holes 40 into the heating chamber 42 and then upwardly and back into the stack of the cupola again through the upper holes 4|. The holes 49, the heating chamber 42 and the upper holes 4| thereby form a by-pass by which the hot gases of the cupola are taken out of the side of the walls of the cupola, heat removed from the hot gases in the heating chamber, and the gases thereupon reintroduced back into the stack of the cupola from whence they are carried up out into atmosphere from the top of the cupola.

Inasmuch as the tubular conduits 39 arev spaced apart and are also spaced away from the outer walls of the wind box andthewall of the cupola the hot gases in the heating chamber may freely circulate around within the chamber and entirely surround the conduits 3.9 through which the air is pasing. The tubular conduits 39 have a relativelylarge expanse ofv heat exchange surface and all of this large expanse of heat exchange surface is utilized in the heating of the air within the conduitsby the hot gases surrounding the conduits.

As the heat is equally distributed to all of the conduits and all of the conduits accommodate an equal supply of air there is a uniform heatin'g of all portions of the air blast delivered to the lower portions of the wind box and then into the tuyres.y The greatest degree of heat exchange is obtained by the arrangement of the plurality of conduits containing the air iiow and surrounded by the hot gases. .The arrangement conserves the heat for a maximum utilization thereof in pre-heating the air supplied to the tuyres bythe air supply system.

A modified form of the invention is illustrated in Figures and 4. In this arrangement the upper portion of the wind box and the lower portion of the wind box are separated by a piurality of tubular conduits 44, the partitions 31Yand 38 in eil'ect dividing the wind box into two separate compartments. between the air and the hot gases in the modified arrangement o f Figures 3 and 4. A plurality of pipes or conduits 45 are disposed within and ex` tend longitudinally of the tubes 44, the pipes 45 being of smaller diameter than the tubes 44. The pipes 45 have connecting portions extending inwardly to communicate with the interior of the cupola through the walls thereof, the lower holes 46 providing communication with the lower end of the pipes 45 and the upper holes 41 pro- There is a reversal of Ypositiony tubular conduits operation of the same.

.n t y'2,273,901 viding communication with the upper end `of the pipes 45.J Hot gases are therefore by'`passed out through the holes"48 upwardly throughthe pipes the shaft of the cupola through rounds the'pipes45 through which the hot gases flow. A' maximum amount of heat exchange surfaceis afforded by the tubular pipe 45` and this change between the hot lgases andthe air to be heated. The pipe Vconduits Iare of uniform size 'and are uniformlyarrangedaround the outside 'of thebody ofthe cupola. 'The air flowing from "the upper portion of the wind box down through *the conduits 44'- isuniformly heated to besupplied to the plurality of `tuyres from the lowe portion 'of thewind box. a A protecting` ledge 48- mounted to the inner wallfof the cupola slightly Voverhangs-the holes 41 andlprevents solidmaterials suchrascoke and metal from entering `the holes 41 andlodgingin "the system. Althougli'thel hotz gases in .both

'forms of the invention have been shown to vbebypassed in heat exchangefrelationship with the `air and then brought back into the shaft of the cupola-it is"also-pos'sibley to have the =hot"gass flow out-into atmosphere through separate-nues xafter'the utilizationof-the heat thereof. However; it is more practical and economical to' uti;-

lize the shaft of the cupolafoncarryingofl the gasesafter thelheat exchange hastaken place.

. 3 of the wind box adjacent lthe tuyres, said fur- `nace having openings through the walls thereof to` provide communication between the'v interior of the furnace and said hot gaschamber for the flow of hot' gases generated by the furnace .through said hot gas chamber, therair supplied toLsaid tuyres'being pre-heatedrby heat exjchange with said hot gases.

'maximum amount of surfacer is fullyutilized by: the arrangement shownjfor an eicient heat exn 2. In a furnace having a wind `box positioned around the body of the furnace for supplying blown air to a plurality of tuyres communicating with the furnace, said wind box having an inlet adapted to communicate with `a sourceof blown air, a'heater positioned in said wind box y,and extending around the annularextent thereof 'Jin uniform `proximity `to said tuyres, said heater dividing the wind box into a chamber im- `m'ed'iately above, and a chamber immediately be low, the said' heater, said chamber above the heater r,communicating with the inlet .and said chamber` below the heater communicating with the tuyres,`a plurality of conduitstconnecting By both vof the arrangements'shown aneiiicient heat exchange-'system is utilized for the pre-heating of the air supply for a cupola by the heat generated within the cupola inthe usual It is to be noted that there is not only a uniform heating of the air blast but also that the air after being heated is subjected to uniform heat exchange conditions in passing to the tuyres, the heating arrange- 'rnent being positioned in the same 'proximity' kto the tuyres at all points around the cupola.

Although we have described our invention with r a certain degree of particularity. it is understood that the present disclosure has been made only by way of example and that numerous changes in` the detailsv of constructionfand the combination 'I claim as my invention:

1. In a furnace having a wind box positioned around the body of the furnace for supplying o blown air to a plurality of tuyres communii therebetween, a plurality of conduits extending through said intermediate portion yto provide communication for the flowvof air from the portion adjacent the inlet to the portion adjacent the tuyres, said intermediate portion having a hot gas chamber provided therein, said hot gas chamber substantially surrounding said conduits and arrangement of parts may be resorted to` without departing from the spirit and the scope of the invention as hereinafter claimed. l

for heating the air flowing therein and substanf tially extending between the said portion of the wind box adjacent the inlet and the said portion said upperand lower chambers for passing air,l in

the wind box through said heaterfrom the upper of said chambers tothe lower of saidchambers,

` said lconduits being uniformly V distributed around jthe wind-box` to `equalize the flow therethrough,

and connectingmeans connecting said, heater ywith the interior of `the furnace to by-pass hot gases from the furnace through said heater, the l hotjgases in*` said heater substantially surrounding 'said conduits to heat theair flowing therethrough to said tuyres.

i 3. In a furnace" having awind .box positioned 'arounduthe body of thelfurnace for supplying blown airfto a plurality `of tuyres communicatin'giwith the furnace, said windbox having an inlet adapted to communicate" with a source of blown"air,` a plurality of 4air conduits spaced ,at intervals around the body of the furnace and extending between a. portionV of the wind box adjacent the inlet forming an upper chamber and a portion of the wind box adjacent the tuyres forming a lowerchamber for providing com- `municationv for the flow of air therebetween, a

plurality of hot gas conduits disposed within, and spacedy from the sides of, said air conduits, respectively, to heat the air passing through said air conduits, said 'hot gas conduits extending substantially the length of said air conduits from adjacent one of said chambers to adjacent the other of saidA chambers, and upper and lower connecting conduits extending through the wall ofthe furnace and connecting saidhot gas conduits with the interior of thefurnace for bypassing hot gases generated by the furnace throughthe said hot gas conduits.

` 4. In a furnace having a wind box positioned around the body of the furnace for supplying blown air toa plurality of ytuyres communicating with the furnace, said wind box having an inlet adapted'to communicate with a source of blown air, a plurality of tubes for distributing equalportions of the blown air from the portion of the wind box adjacent the inlet forming an upper chamber to the Portion of the wind box adjacent the tuyres forming a lower chamber,

'and a plurality ofpipes extending within, and

longitudinally of, said tubes substantially co-extensively therewith, said pipes being connected through the furnace body with -the interior of the furnace to provide for the flow of hot gases genv tubes and being heated thereby prior to entering said tuyres.

, 5. Ina furnace having a Wind box for supplying a. blast of airltoa plurality of` tuyres, said l vwind box having an upper' chamber encircling said furnace and alower chamber encircling said furnace, said upper chamber having an inlet adaptedto communicateV with a source of an air blast and said lower chamber having outlets in communication with said tuyres and having a plurality of separate and uniformly spaced air Aconduits disposed around the circumferential extent of the furnace to provide communication between said upper and lower chambers, means for heating the air insaid conduits comprising a plurality of holes extending through the wallv of the'furnace adjacent to, and below, said upper chamber and adjacentto, and above, said lower chamber, and intermediate chamber means providing communication between the upper and lower holes, said intermediate chamber means beingpositioned in heat exchange yrelationship y `with., and being extended'along substantially the lengthv of, said `air conduits, the air passing through said air conduits being heated in its travel therethrough from therupper chamber to the lower chamber by the hot gases by-pas'sed through said holes from the furnace and through the intermediate chamber means.

fi.; Apparatus for pre-heating air delivered to a furnace through a plurality jof tuyresV comprising, in combination, air chamber means and 2,273,901 said pipes along substantially the length of the nace, and a plurality of spaced conduits extendo ing between saidupper and'lower chambers at uniformintervals around the furnace to provide communication between said upper and lower chambers, said hot gas chamber means being positioned intermediate of said uppery and lower lchambers of the air chamber means and being extended longitudinally of the furnace substantially the length of said spaced conduits, said hot gas chamber means being in communication through the furnace wall with the interior of the furnace to permit hot gases from the furnace to flow therethrough, the air insad conduits being heated substantially throughout its travel from the upper chamber to the lower chamber by said hot gas chamber means.

7. In a systemfor pre-heating air delivered through a plurality of tuyres to a furnace by the exchange of hot gases. generated within the furnace, an upper compartment positioned around the body of the furnacer and having an inlet in'communication witha source of blown air, a lower compartment positioned around the body of thefurnace and in communication with said plurality of tuyres, a-plurality of conduits substantially .uniformly distributed around the body of the furnace and providingfor the uniform flow of air .therethrough from said upper compartment-to. said lower compartment, and by-passing means in communication with the interiory ofthe furnace for by-passing hot gases outsidevof the body of the furnace,A said by-pass;- ing means extending substantially between said upper and lower compartments and along the vextent of said conduits, the air being heated in 

